It is a regrettable fact that in the day to day operation of a motor vehicle, there is a chance that an impact event may occur. Accordingly, all automobile manufacturers have continuously looked to improve the safety features of motor vehicles. One such safety feature is the airbag, now common in most modern motor vehicles. In order to deploy the airbag, the motor vehicle must know when an impact event is occurring as soon as possible after the start of the impact event.
One common method of determining when an impact event has started is the use of an accelerometer located within the motor vehicle that senses the change in velocity of the motor vehicle. While this device has served very well in the past, a single accelerometer is not efficient at sensing “off-set impacts” (e.g., impacts occurring to a front corner of the motor vehicle). A solution has been to add more accelerometers within the crush zone (e.g., the forward bumper area of the motor vehicle) to detect the impact event. Again, while useful for its intended purpose, these accelerometers do not tend to be consistent between test crashes and are therefore difficult to calibrate. Moreover, during a washout impact wherein the vehicle bottoms out in a puddle thereby jostling the vehicle, a period of time must pass (10 to 15 milliseconds) to determine if the accelerometers are reading an impact event that would require airbag deployment or whether a puddle impact has occurred. Accordingly, efforts have been made to reduce the time needed to distinguish between impact events and puddle impacts or any other impact not requiring deployment of the airbag.